f 101 



collar. It is also firmer mechanically and resists the 

 tendency to be blown out by slight internal pressures 

 in the can, This tendency to resist blow-out is in- 

 creased, also, by the cotton plug in the lower part of the 

 sealing-wax collar. At the same time the grafting-wax plug 

 remains sufficiently plastic to permit expansion of the 

 stea» by growth. The important considerations in making 

 the seal are, first, to have the annular space between 

 the stem and the sealing-wax collar long enough and 

 not too wide, and, second, to apply the grafting-wax at 

 the proper viscosity, which means the proper temperature. 

 The necessity of this proper temperature has already 

 been explained. If the annular space for the grafting- 

 wax plug is too short or too wide the seal will blow 

 out. Under most conditions the dimensions given above 

 will be fully satisfactory. It is also necessary, of 

 course, to use great care not to burn the plant when 

 soldering-in the top or sealing- down the collar and 

 various seals of sealing wax. The flame of the gas- 

 blowpipe should be made very short ( not over 2 cm.) 

 and handled carefully. If desired, the plant can be 

 protected by an inverted cone of asbestos paper wrapped 

 about it and supported from above by a ring-stand and 

 clamp, but this precaution is unnecessary with suffi- 

 cient care and skill in handling the gas-blowpipe. In 

 making the soldered joints no acid or other flux should 



